The structure formation upon cooling of the quiescent melt of a nearly defect-free isotactic poly(propylene) (ipp) homopolymer is investigated in this study. this ipp has a molecular weight of 1 x 10° g/mol and a narrow molecular weight distribution. information about the crystallization kinetics is collected in a broad range of cooling rates. standard differential scanning calorimetry is used at cooling rates in the range 3-100c/min. the near absence of regio- and stereo-defects allows this ipp to crystallize at significantly higher temperatures and to form crystals at higher cooling rates than commonly observed for standard ipp. the data reveal that the ipp homopolymer with close-to-perfect stereo-regularity forms crystals at high cooling rates. the defect-free polymer chain allows the formation of relatively thick lamellar crystals having a relatively high tensile modulus of 20888 mpa. macromolecular chemistry and physics, 216(22), 2171-2178 (2016) a) provide a rough sketch of a dsc plot comparing the heat evolution of a sample of "defect free" ipp versus 'normal' ipp. normal polypropylene has a tm of 130°c b) why does the near absence of defects allow this ipp to crystallize at higher temperatures than for 'normal' ipp? c) why does the near absence of defects allow this ipp to crystallize thicker crystals than observed for 'normal' ipp? provide a rough quantitative estimate of crystal thickness d) why is the tensile modulus of these crystals higher than that of crystals formed from 'normal' ipp?